Analysis of PD-L1 Transcriptional Regulation in Ovarian Cancer Cells by Chromatin Immunoprecipitation.

The immune checkpoint molecule, programmed death ligand 1 (PD-L1; B7-H1, CD274), induces T cell apoptosis and tolerance, thus inhibiting the antitumor immunity. PD-L1 expression is increased in many types of cancer, including ovarian cancer (OC), and correlates with poor prognosis. However, the mechanisms that regulate the PD-L1 expression in cancer cells are incompletely understood. The transcriptional regulation of PD-L1 expression is orchestrated by several transcription factors, including NFκB. The human PD-L1 promoter contains five NFκB-binding sites. Interferon-γ (IFNγ) stimulation of OC cells induces p65, and particularly K314/315 acetylated p65 recruitment to all five NFκB-binding sites in PD-L1 promoter, resulting in increased PD-L1 expression. In this chapter, we describe a protocol that uses chromatin immunoprecipitation (ChIP) to analyze the transcriptional regulation of PD-L1 by measuring recruitment of NFκB p65 and K314/315 acetylated p65 to PD-L1 promoter in human OC cells.